In many applications, semiconductor chips are mounted onto a metallic substrate, a so-called leadframe. To do so, the leadframes are presented in magazines or on a stack from where they are removed by a robot and fed to the transport device of an automatic assembly machine, a so-called Die Bonder, that transports the leadframes one after the other to a dispensing station where adhesive or solder is applied and to a bonding station where the semiconductor chip is deposited.
The transport device consists for example of a system of fixed and moveable clamps that hold the leadframe on a longitudinal edge. This longitudinal edge of the leadframe rests on a guide rail. Such a transport device is known from U.S. Pat. No. 5,163,222 or CH 689 188.
The robot has suction grippers with which one leadframe after the other is removed from the stack and placed onto a support surface of the transport device. A pusher device pushes the leadframe against the guide rail of the transport device by means of a slide so that one of its longitudinal edges rests against the guide rail. The leadframe is now aligned so that it can be transported by the clamps to the dispensing station and then to the bonding station. The support surface has grooves running at right angles to the transport direction in order to be able to connect the slide to a drive arranged underneath the support surface. This solution has two significant disadvantages. One is that very often the fingers of a leadframe get caught in one of these grooves whereby the leadframe is damaged and unusable. The other is that each time the leadframe type is changed, the travel distance, ie, the distance, that has to be covered by the slide has to be reset by hand corresponding to the width of the new leadframe.